Add optional extcon notifier support to enable the hotplug / unplug of the underlying PHY layer devices.
If supported, the Device Tree (DT) node for the device should include an "extcon" property which is a phandle to an extcon DT node. This patch is an effort to incorporate the equivalent support from the Rockchip dwc3 driver implementation from Chrome OS [1] to the mainline. [1] : https://chromium.googlesource.com/chromiumos/third_party/kernel/ +/refs/heads/chromeos-4.4/drivers/usb/dwc3/dwc3-rockchip.c Cc: Benson Leung <ble...@chromium.org> Cc: Guenter Roeck <gro...@chromium.org> Cc: Enric Balletbo i Serra <enric.balle...@collabora.com> Signed-off-by: Prashant Malani <pmal...@chromium.org> --- drivers/usb/dwc3/dwc3-of-simple.c | 149 +++++++++++++++++++++++++++++- 1 file changed, 146 insertions(+), 3 deletions(-) diff --git a/drivers/usb/dwc3/dwc3-of-simple.c b/drivers/usb/dwc3/dwc3-of-simple.c index e64754be47b4..28bde27cd1f9 100644 --- a/drivers/usb/dwc3/dwc3-of-simple.c +++ b/drivers/usb/dwc3/dwc3-of-simple.c @@ -11,6 +11,7 @@ * by Subbaraya Sundeep Bhatta <subbaraya.sundeep.bha...@xilinx.com> */ +#include <linux/extcon.h> #include <linux/module.h> #include <linux/kernel.h> #include <linux/slab.h> @@ -29,8 +30,117 @@ struct dwc3_of_simple { struct reset_control *resets; bool pulse_resets; bool need_reset; + struct extcon_dev *edev; + struct notifier_block nb; + struct work_struct work; + /* Denotes whether child devices have been populated. */ + bool populated; + bool suspended; + spinlock_t suspend_lock; }; +static int dwc3_of_simple_populate(struct dwc3_of_simple *simple) +{ + struct device *dev = simple->dev; + struct device_node *np = dev->of_node; + int ret; + + ret = of_platform_populate(np, NULL, NULL, dev); + if (ret) { + dev_err(dev, "Failed to populate dwc3 devices.\n"); + return ret; + } + simple->populated = true; + return 0; +} + +static void dwc3_of_simple_depopulate(struct dwc3_of_simple *simple) +{ + if (simple->populated) { + of_platform_depopulate(simple->dev); + simple->populated = false; + } +} + +static void dwc3_of_simple_work(struct work_struct *work) +{ + struct dwc3_of_simple *simple = container_of(work, + struct dwc3_of_simple, work); + struct extcon_dev *edev = simple->edev; + + if (extcon_get_state(edev, EXTCON_USB_HOST) > 0) { + if (simple->populated) + return; + + dwc3_of_simple_populate(simple); + } else { + if (!simple->populated) + return; + + dwc3_of_simple_depopulate(simple); + } +} + +static int dwc3_of_simple_notifier(struct notifier_block *nb, + unsigned long event, void *ptr) +{ + struct dwc3_of_simple *simple = container_of(nb, struct dwc3_of_simple, + nb); + unsigned long flags; + + spin_lock_irqsave(&simple->suspend_lock, flags); + if (!simple->suspended) + schedule_work(&simple->work); + spin_unlock_irqrestore(&simple->suspend_lock, flags); + + return NOTIFY_OK; +} + +static int dwc3_of_simple_extcon_register(struct dwc3_of_simple *simple) +{ + struct device *dev = simple->dev; + struct extcon_dev *edev; + int ret; + + edev = extcon_get_edev_by_phandle(dev, 0); + if (IS_ERR(edev)) { + /* The extcon property is optional. */ + if (PTR_ERR(edev) == -ENODEV) + return 0; + if (PTR_ERR(edev) != -EPROBE_DEFER) + dev_err(dev, "Couldn't get extcon device.\n"); + return PTR_ERR(edev); + } + + INIT_WORK(&simple->work, dwc3_of_simple_work); + + simple->nb.notifier_call = dwc3_of_simple_notifier; + ret = devm_extcon_register_notifier(dev, edev, EXTCON_USB_HOST, + &simple->nb); + if (ret < 0) { + dev_err(dev, "Failed to register notifier.\n"); + return ret; + } + + simple->edev = edev; + + return 0; +} + +static void dwc3_of_simple_extcon_unregister(struct dwc3_of_simple *simple) +{ + if (!simple->edev) + return; + + /* + * We explicitly unregister the notifier to prevent races with + * the of_depopulate() call in remove(). + */ + devm_extcon_unregister_notifier(simple->dev, simple->edev, + EXTCON_USB_HOST, &simple->nb); + cancel_work_sync(&simple->work); +} + static int dwc3_of_simple_probe(struct platform_device *pdev) { struct dwc3_of_simple *simple; @@ -47,6 +157,8 @@ static int dwc3_of_simple_probe(struct platform_device *pdev) platform_set_drvdata(pdev, simple); simple->dev = dev; + spin_lock_init(&simple->suspend_lock); + /* * Some controllers need to toggle the usb3-otg reset before trying to * initialize the PHY, otherwise the PHY times out. @@ -87,9 +199,24 @@ static int dwc3_of_simple_probe(struct platform_device *pdev) if (ret) goto err_resetc_assert; - ret = of_platform_populate(np, NULL, NULL, dev); - if (ret) + ret = dwc3_of_simple_extcon_register(simple); + if (ret < 0) { + dev_warn(dev, "No extcon device found, err: %d\n", ret); goto err_clk_put; + } + + if (!simple->edev) { + ret = dwc3_of_simple_populate(simple); + if (ret) + goto err_clk_put; + } else { + /* + * Populate through worker to avoid race conditions against + * action scheduled through notifier. + */ + if (extcon_get_state(simple->edev, EXTCON_USB_HOST) > 0) + schedule_work(&simple->work); + } pm_runtime_set_active(dev); pm_runtime_enable(dev); @@ -112,7 +239,8 @@ static int dwc3_of_simple_probe(struct platform_device *pdev) static void __dwc3_of_simple_teardown(struct dwc3_of_simple *simple) { - of_platform_depopulate(simple->dev); + dwc3_of_simple_extcon_unregister(simple); + dwc3_of_simple_depopulate(simple); clk_bulk_disable_unprepare(simple->num_clocks, simple->clks); clk_bulk_put_all(simple->num_clocks, simple->clks); @@ -163,6 +291,13 @@ static int __maybe_unused dwc3_of_simple_runtime_resume(struct device *dev) static int __maybe_unused dwc3_of_simple_suspend(struct device *dev) { struct dwc3_of_simple *simple = dev_get_drvdata(dev); + unsigned long flags; + + spin_lock_irqsave(&simple->suspend_lock, flags); + simple->suspended = true; + spin_unlock_irqrestore(&simple->suspend_lock, flags); + + cancel_work_sync(&simple->work); if (simple->need_reset) reset_control_assert(simple->resets); @@ -173,10 +308,18 @@ static int __maybe_unused dwc3_of_simple_suspend(struct device *dev) static int __maybe_unused dwc3_of_simple_resume(struct device *dev) { struct dwc3_of_simple *simple = dev_get_drvdata(dev); + unsigned long flags; if (simple->need_reset) reset_control_deassert(simple->resets); + spin_lock_irqsave(&simple->suspend_lock, flags); + simple->suspended = false; + spin_unlock_irqrestore(&simple->suspend_lock, flags); + + if (simple->edev) + schedule_work(&simple->work); + return 0; } -- 2.27.0.rc0.183.gde8f92d652-goog
